Ms. Yingyan Lou

University of Florida, USA

January 23, 2009, 10:15, Room GC C3 30 (click here for the map)

Robust Pricing with Boundedly Rational User Equilibrium

This research investigates congestion pricing strategies in static networks with boundedly rational route-choice behaviors. Under such behavior, users do not necessarily choose a shortest or cheapest route, when doing so does not reduce their travel time by a significant amount. A general path-based definition and a more restrictive link-based representation of boundedly rational user equilibrium (BRUE) are presented. The set of BRUE flow distributions are non-convex and always non-empty. The problems of finding best- and worst-case BRUE flow distributions are formulated and solved as mathematical programs with complementarity constraints. Because alternative tolled BRUE flow distributions exist, our congestion pricing models seek a toll vector or scheme that minimizes the system travel time of the worse-case tolled BRUE flow distribution. As formulated, the models are generalized semi-infinite min-max problems, and we propose a heuristic algorithm based on penalization and a cutting-plane scheme to solve them. Numerical experiments demonstrate that system performance may vary substantially within the BRUE set, and traditional marginal-cost pricing may not evolve the flow distribution to system optimum. The proposed robust pricing models are able to guard against the worst-case scenario effectively and lead to a more stable system performance. This research offers a new alternative for more realistically modeling users' route choices at general networks. It has relaxed the dominance of the assumption of perfect rationality in transportation planning, and led to more realistic models and accurate tools to help and guide in the analysis and evaluation of congestion pricing strategies.


Yingyan Lou is a Ph.D. candidate in the Department of Civil and Coastal Engineering at the University of Florida. She received two bachelor degrees in both Engineering Science and Economics from Peking (Beijing) University, China, in 2005; and earned her master degree in Civil Engineering from the University of Florida in 2007. Yingyan Lou is currently a research assistant at the Transportation Research Center, University of Florida. Her primary research interest is transportation systems modeling and optimization, with applications on system-wide congestion pricing, traffic-responsive tolling for managed-lane operations, dynamic origin-destination demand estimation, robust transportation network design, freeway incident response planning, and infrastructure asset management. She also has a keen interest in traffic flow theory and operations. During her Ph.D. study, Yingyan Lou has co-authored seven papers and made eight presentations at various conferences. She won the best poster award at the 2007 Institute of Transportation Engineers Florida District Annual Meeting and was awarded the graduate scholarship of Women's Transportation Seminar in 2008.